This invention relates to 1,2,4-oxadiazole compounds substituted in the 3-position with a (chlorophenylsulfonyl)methyl or chlorophenylsulfonyl)ethyl group and variously substituted in the 5-position with carboxylic acid derivatives, such as carboxylic acid salts, esters, or hydrazine derivatives; and the pharmacologically acceptable acid addition salts of such compounds which have a bsic nitrogen moiety. Except where Z is NHNH.sub.2, said compounds exhibit antihypertensive activity in standard pharmacological tests in animals; compounds where Z is --NHNH.sub.2 exhibit antiviral activity against influenza B Mass. virus.